The overall objectives of this project are to investigate the regulation of transport activity in lymphocytes and, specifically, to delineate the mechanisms by which mitogens stimulate transport activity. In the early stages of this project, the effects of anaerobiosis and sulfhydryl reagents on the rate of 3-O-methylglucose transport by rat thymocytes will be investigated in the hopes that an understanding of the regulatory properties of this transport system will be helpful in interpreting the effects of mitogens on 3-O- methylglucose transport. These studies will later be extended to include the effects of mitogens on transport of alpha-aminoisobutyric acid, uridine and Rb ion. Finally, efforts will be made to prepare membrane vesicles from rat thymocytes, to study their transport properties and to examine the effects of mitogens on transport activity in these vesicles.